1. Field of the Invention
This invention generally relates to a faucet hydroelectric generator, and more particularly a faucet hydroelectric generator generating electric power using a flow of water supply.
2. Description of the Related Art
Recently, faucet devices have often been equipped with electrical systems. For instance, there is known a faucet device equipped with a sensor for sensing a hand stretched out below the tap, and a solenoid valve for opening/closing the water supply channel based on the signal from the sensor. As another example, an LED (light emitting diode) lamp is incorporated near the water discharge port to change the color of light shed on the discharged water in accordance with the temperature of the discharged water.
If such an electrical system is incorporated in a faucet device, a power supply for operating the electrical system is required. This requirement can be met by using utility power. However, electrical wiring work is separately needed when the faucet device is installed. Furthermore, because the wiring is installed outside the faucet device, the wiring may degrade the appearance and cause a nuisance. On the other hand, if a battery is used as a power supply, there is no need to conduct electrical wiring work when the faucet device is installed. Furthermore, there is no need to install the wiring outside the faucet device. However, use of a battery as a power supply causes another problem of requiring battery replacement, which takes time and effort of maintenance. Furthermore, irrespective of whether utility power or a battery is used, a problem occurs from the viewpoint of resource saving and energy saving.
Thus, a small faucet hydroelectric generator is often disposed in the flow channel of the faucet device in order to obtain electrical power required for the operation of the electrical system incorporated in the faucet device.
In one of such faucet hydroelectric generators known in the art, water flows in from radially outside the bucket, and the inflow water flows out in the axial direction of the bucket (see, e.g., Patent Document 1).
The faucet hydroelectric generator disclosed in Patent Document 1 (JP-A-2009-047162) includes a nozzle for changing the direction of water flow generally parallel to the axial direction of the bucket to squirt water from radially outside the bucket blade toward the bucket blade. Furthermore, the configuration is such that the water squirted at the bucket blade flows out in the axial direction of the bucket near the center of the bucket. Furthermore, a ceiling 15d (corresponding to the lid in this invention) is provided on the upstream end surface of the bucket blade (see, e.g., paragraphs 0074 and 0080, FIGS. 14 to 20, etc. in Patent Document 1 (JP-A-2009-047162)).
In the faucet hydroelectric generator disclosed in Patent Document 1 (JP-A-2009-047162), the radial dimension can be decreased. Furthermore, the amount of outflow to the bypass flow channel can be suppressed. Hence, the variation of jet flow impinging on the respective bucket blades can be suppressed.
Here, the faucet hydroelectric generator disposed in the flow channel of the faucet device is generally intended for use at low flow rate. Thus, the faucet hydroelectric generator disclosed in Patent Document 1 (JP-A-2009-047162) can also achieve very high performance without any problem at low flow rate. However, it turns out that wear of the bearing portion may increase at high flow rate.
As the result of close study, the inventors have ascertained that the wear increase of the bearing portion is caused by the increase of thrust force acting on the bucket.
FIG. 30 is a schematic view for describing the thrust force acting on the bucket. The arrows depicted in the figure indicate the direction of flowing water.
As shown in FIG. 30, the faucet hydroelectric generator 60 includes a cylinder portion 67, a nozzle portion 63, a rotor 64, and a magnet 65. Furthermore, although not shown, a stator is provided outside the cylinder portion 67 so as to be opposed to the outer peripheral surface of the magnet 65. The rotor 64 includes a lid 61 (corresponding to the ceiling 15d in Patent Document 1 (JP-A-2009-047162)), a bucket 62, and a shaft 63. The lid 61 is provided at the upstream end of the bucket blade 62a. The downstream end portion of the shaft 63 is supported by a bearing portion 66, and the upstream end portion thereof is supported by a bearing, not shown. Hence, the force in the thrust direction applied to the bucket 62 is sustained by the bearing portion 66.
The lid 61 thus provided at the upstream end of the bucket blade 62a can eliminate water flowing out from the bucket blade 62a to the upstream side. This can increase water flowing in the bucket flow channel, and hence increase the power generation efficiency.
Here, between the lid 61 and the ceiling 67a of the cylinder portion 67, the rotary motion of water flow occurs due to the rotation of the rotor 64. However, it is difficult for the water to flow out from between the lid 61 and the ceiling 67a. Hence, the pressure tends to build up therebetween. Thus, the pressure of water between the lid 61 and the ceiling 67a increases and generates a force pushing the lid 61 to the downstream side, i.e., a thrust force 110 acting on the bucket 62. The generation of the thrust force 110 may increase wear of the bearing portion 66 supporting the thrust force 110 and of the end portion of the shaft 63.
According to the findings obtained by the inventors, the generated thrust force 110 is small at flow rates suitable for use of the faucet hydroelectric generator disclosed in Patent Document 1 (JP-A-2009-047162), such as approximately 1.8 liters/min (see, e.g., paragraphs 0061, 0063, 0065, etc. in Patent Document 1 (JP-A-2009-047162)). Hence, it can be said that there is no danger of abnormal wear of the bearing portion 66.
However, with the increase of flow rate, the generated thrust force 110 increases. Hence, there is demand for improvement of the faucet hydroelectric generator also used at relatively high flow rate (such as approximately 8 liters/min or more). That is, it is desired that the power generation efficiency is high even for power generation at relatively high flow rate, while wear of the bearing portion can also be suppressed.